A voltage scanning-based MPPT method for PV power systems under complex partial shading conditions

2021 ◽  
Author(s):  
Resat Çelikel ◽  
Musa Yılmaz ◽  
Ahmet Gündoğdu
Keyword(s):  
Power Systems ◽  
Partial Shading ◽  
Voltage Scanning

scholarly journals New Control Scheme for Solar Power Systems under Varying Solar Radiation and Partial Shading Conditions

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1359
Author(s):  
Anindya-Sundar Jana ◽  
Hwa-Dong Liu ◽  
Shiue-Der Lu ◽  
Chang-Hua Lin
Keyword(s):  
Solar Radiation ◽  
Power Systems ◽  
High Efficiency ◽  
Rapid Change ◽  
Maximum Power ◽  
Maximum Power Point ◽  
Partial Shading ◽  
Detection Scheme ◽  
Threshold Control ◽  
Power Point

The traditional perturbation and observation (P&O) maximum power point tracking (MPPT) algorithm of a structure is simple and low-cost. However, the P&O algorithm is prone to divergence under solar radiation when the latter varies rapidly and the P&O algorithm cannot track the maximum power point (MPP) under partial shading conditions (PSCs). This study proposes an algorithm from the P&O algorithm combined with the solar radiation value detection scheme, where the solar radiation value detection is based on the solar photovoltaic (SPV) module equivalent conductance threshold control (CTC). While the proposed algorithm can immediately judge solar radiation, it also has suitable control strategies to achieve the high efficiency of MPPT especially for the rapid change in solar radiation and PSCs. In the actual test of the proposed algorithm and the P&O algorithm, the MPPT efficiency of the proposed algorithm could reach 99% under solar radiation, which varies rapidly, and under PSCs. However, in the P&O algorithm, the MPPT efficiency was 96% under solar radiation, which varies rapidly, while the MPPT efficiency was only 80% under PSCs. Furthermore, in verifying the experimental results, the proposed algorithm’s performance was higher than the P&O algorithm.

scholarly journals Optimal Array Reconfiguration of a PV Power Plant for Frequency Regulation of Power Systems

2021 ◽  
Vol 9 ◽  
Author(s):  
Tingyi He ◽  
Shengnan Li ◽  
Yiping Chen ◽  
Shuijun Wu ◽  
Chuangzhi Li
Keyword(s):  
Power Plant ◽  
Power Systems ◽  
Pareto Front ◽  
Frequency Control ◽  
Storage System ◽  
Energy Storage System ◽  
Automatic Generation ◽  
Frequency Regulation ◽  
Nsga Ii ◽  
Partial Shading

This paper establishes a novel optimal array reconfiguration (OAR) of a PV power plant for secondary frequency control of automatic generation control (AGC). Compared with the existing studies, the proposed OAR can further take the AGC signal responding into account except the maximum power output, in which the battery energy storage system is used to balance the power deviation between the AGC signals and the PV power outputs. Based on these two conflicted objects, the OAR is formulated as a bi-objective optimization. To address this problem, the efficient non-dominated sorting genetic algorithm II (NSGA-II) is designed to rapidly obtain an optimal Pareto front due to its high optimization efficiency. The decision-making method called VIKOR is employed to determine the best compromise solution from the obtained Pareto front. To verify the effectiveness of the proposed bi-objective optimization of OAR, three case studies with fixed, step-increasing, and step-decreasing AGC signals are carried out on a 10 × 10 total-cross-tied PV arrays under partial shading conditions.

A Hybrid Model of Photovoltaic Power Stations for Model Ling Tasks of Large Power Systems

2021 ◽  
Vol 69 (4) ◽  
pp. 43-49
Author(s):  
Nikolay RUBAN ◽  
◽  
Vladimir RUDNIK ◽  
Igor RAZZHIVIN ◽  
Anton KIEVEC ◽  
...  
Keyword(s):  
Power Systems ◽  
Power System ◽  
Power Station ◽  
Partial Shading ◽  
Large Power ◽  
Photovoltaic Panels ◽  
Power Stations ◽  
Photovoltaic Power ◽  
Software And Hardware ◽  
The Impact

Renewable energy sources are being actively penetrated in the global energy sector, with the main growth being achieved by new photovoltaic power stations. At the same time, the influence of photovoltaic power stations on the operation of power systems is known. This is primarily due to the inconstancy of the weather, which leads to a decrease in the output of each specific photovoltaic panel and power station as a whole. To study the effect of partial shading of photovoltaic panels on the parameters of its operation, various models of the current-voltage characteristics of photovoltaic cells are used in the world, while detailed two-diode models show the best results. The use of detailed models allows to get complete information about the processes in a variety of photovoltaic panels of a power station, as well as other elements of it, such as a voltage converter. This makes it possible to assess the impact of these processes on the external power system. However, for detailed modelling of large photovoltaic power stations as part of power systems, it is necessary to use powerful software and hardware systems. Such systems include the Hybrid real-time power system simulator. This simulator is a multiprocessor installation that provides a solution to the aggregate model of the power system through the use of three approaches to modelling: digital, analogue and physical. The article presents the results of experimental studies of software and hardware tools for modelling a photovoltaic power station, developed on the basis of a hybrid approach to modelling electric power systems.

High-Voltage Scanning Electron Microscopy

1970 ◽  
Vol 28 ◽  
pp. 6-7
Author(s):  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Wave Optics ◽  
Contrast Effects ◽  
Transmission Electron ◽  
Mode Of Operation ◽  
Scanning Transmission ◽  
Types Of Information ◽  
Voltage Scanning

The comparison of scanning transmission electron microscopy (STEM) with conventional transmission electron microscopy (CTEM) can best be made by means of the Reciprocity Theorem of wave optics. In Fig. 1 the intensity measured at a point A’ in the CTEM image due to emission from a point B’ in the electron source is equated to the intensity at a point of the detector, B, due to emission from a point A In the source In the STEM. On this basis it can be demonstrated that contrast effects In the two types of instrument will be similar. The reciprocity relationship can be carried further to include the Instrument design and experimental procedures required to obtain particular types of information. For any. mode of operation providing particular information with one type of microscope, the analagous type of operation giving the same information can be postulated for the other type of microscope. Then the choice between the two types of instrument depends on the practical convenience for obtaining the required Information.

Processing of human melanoma cells for correlative TEM, LVSEM, and LM

1991 ◽  
Vol 49 ◽  
pp. 106-107
Author(s):  
Marek Malecki ◽  
J. Victor Small ◽  
James Pawley
Keyword(s):  
Electron Microscopy ◽  
Low Voltage ◽  
Fluorescent Microscopy ◽  
Blood Stream ◽  
Surface Topology ◽  
Integrin Receptors ◽  
Transmission Electron ◽  
Develop Technology ◽  
Voltage Scanning ◽  
Mechanisms Of Adhesion

The relative roles of adhesion and locomotion in malignancy have yet to be clearly established. In a tumor, subpopulations of cells may be recognized according to their capacity to invade neighbouring tissue,or to enter the blood stream and metastasize. The mechanisms of adhesion and locomotion are themselves tightly linked to the cytoskeletal apparatus and cell surface topology, including expression of integrin receptors. In our studies on melanomas with Fluorescent Microscopy (FM) and Cell Sorter(FACS), we noticed that cells in cultures derived from metastases had more numerous actin bundles, then cells from primary foci. Following this track, we attempted to develop technology allowing to compare ultrastructure of these cells using correlative Transmission Electron Microscopy(TEM) and Low Voltage Scanning Electron Microscopy(LVSEM).

High-pressure freezing of cells in suspension for low-voltage scanning electron microscopy (LVSEM)

1991 ◽  
Vol 49 ◽  
pp. 64-65
Author(s):  
Marek Malecki ◽  
James Pawley ◽  
Hans Ris
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Low Voltage ◽  
Culture Media ◽  
Cell Structure ◽  
Freeze Substitution ◽  
Ice Crystal ◽  
High Pressure Freezing ◽  
Cell Culture Media ◽  
Voltage Scanning

The ultrastructure of cells suspended in physiological fluids or cell culture media can only be studied if the living processes are stopped while the cells remain in suspension. Attachment of living cells to carrier surfaces to facilitate further processing for electron microscopy produces a rapid reorganization of cell structure eradicating most traces of the structures present when the cells were in suspension. The structure of cells in suspension can be immobilized by either chemical fixation or, much faster, by rapid freezing (cryo-immobilization). The fixation speed is particularly important in studies of cell surface reorganization over time. High pressure freezing provides conditions where specimens up to 500μm thick can be frozen in milliseconds without ice crystal damage. This volume is sufficient for cells to remain in suspension until frozen. However, special procedures are needed to assure that the unattached cells are not lost during subsequent processing for LVSEM or HVEM using freeze-substitution or freeze drying. We recently developed such a procedure.

Magnetic Domain Observation of an Amorphous Fe-Si-B Ribbon by Means of a High Voltage Scanning Electron Microscope

1981 ◽  
Vol 39 ◽  
pp. 320-321
Author(s):  
K. Tsuno ◽  
Y. Harada ◽  
T. Sato
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
High Voltage ◽  
Amorphous Ribbon ◽  
Image Resolution ◽  
Objective Lens ◽  
Magnetic Domains ◽  
Scattered Electron ◽  
Voltage Scanning ◽  
Scanning Electron

Magnetic domains of ferromagnetic amorphous ribbon have been observed using Bitter powder method. However, the domains of amorphous ribbon are very complicated and the surface of ribbon is not flat, so that clear domain image has not been obtained. It has been desired to observe more clear image in order to analyze the domain structure of this zero magnetocrystalline anisotropy material. So, we tried to observe magnetic domains by means of a back-scattered electron mode of high voltage scanning electron microscope (HVSEM).HVSEM method has several advantages compared with the ordinary methods for observing domains: (1) high contrast (0.9, 1.5 and 5% at 50, 100 and 200 kV) (2) high penetration depth of electrons (0.2, 1.5 and 8 μm at 50, 100 and 200 kV). However, image resolution of previous HVSEM was quite low (maximum magnification was less than 100x), because the objective lens cannot be excited for avoiding the application of magnetic field on the specimen.

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